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Magnetic dipole moments of the spin-$$\frac{3}{2}$$32 doubly heavy baryons
Abstract
The magnetic dipole moments of the spin-\(\frac{3}{2}\) doubly charmed, bottom and charmed-bottom baryons are obtained by means of the light-cone QCD sum rule. The magnetic dipole moments of these baryons encode essential knowledge of their inner structure and shape deformations. The numerical results are given by \(\mu _{\Xi _{cc}^{*++}} = 2.94 \pm 0.95\), \(\mu _{\Xi _{cc}^{*+}} = - 0.67 \pm 0.11\), \(\mu _{\Omega _{cc}^{*+}} =- 0.52 \pm 0.07\), \(\mu _{\Xi _{bb}^{*0}} = 2.30 \pm 0.55\), \(\mu _{\Xi _{bb}^{*-}} = -1.39 \pm 0.32\), \(\mu _{\Omega _{bb}^{*-}} = -1.56 \pm 0.33\), \(\mu _{\Xi _{bc}^{*+}} = 2.63 \pm 0.82\), \(\mu _{\Xi _{bc}^{*0}} = - 0.96 \pm 0.32\) and \(\mu _{\Omega _{bc}^{*+}} =- 1.11 \pm 0.33\), respectively.
... The numerical results are given in Tables II-XV. In addition, we compare our results with experimental values and other theoretical models, including HBχPT [63,64,[80][81][82][83], the HCQM [56][57][58][59]84], QCDSR [60], CI [61], LQCD [62,72,85], the pion meanfield approach [66], heavy quark symmetry (HQS) [54], the chiral quark model (χQM) [86,87], the chiral constituent quark model (χCQM) [88], the bag model (BM) [76], the NRQM [89], the relativistic three-quark model (RTQM) [90], covariant baryon chiral perturbation theory (BχPT) [91][92][93], the light cone QCD sum rule (LCQSR) [94][95][96][97][98][99][100][101][102][103], the hypercentral model (HCM) [104][105][106], the covariant spectator quark model (CSQM) [107], χPT [108], the chiral quark soliton model (χQSM) [109,110], and the constituent quark model (CQM) [111]. ...
... In contrast to the EMS, our results in SQCS are more compatible with other models [76,81,88,89,105,106]. As shown in Table XI [89], and the HCM [105], except for the LCQSR [99], which predicts larger numerical values among other theoretical models. The numerical predictions for the magnetic moment of Ξ Ãþ cc , however, differ between models. ...
... (iv) The magnetic moments of Ξ Ãþ cc and Ω Ãþ cc are expected to be small, as the contributions of the heavy quarks and the light quark cancel out to some extent due to their opposite signs. However, in the LCQSR [99], the contribution from the light quark dominates over two charm quarks, with a large magnitude leading to larger numerical values. ...
Motivated by the precision measurements of heavy flavor baryon masses, we analyze the modification of quark charge by employing the screening effect inside the baryon. In addition, we calculate the isospin mass splitting up to charmed baryons employing isospin symmetry breaking. Consequently, we obtain the masses, magnetic moments, and transition moments of JP=12+ and 32+ baryons to predict radiative decay widths for 12′+→12+ and 32+→12(′)+ transitions. Finally, we include the effects of state mixing in flavor degenerate baryon magnetic and transition moments, as well as M1 transition decay widths.
... iii. Similarly, for the doubly charmed baryons, our results compare well with the predictions of χCQM [81], NRQM [83], and HCM [93], except for LCQSR [98] which predicts larger numerical values among other theoretical models. The numerical predictions for the magnetic moment of Ξ * + cc , however, differ between models. ...
... The magnetic moments of Ξ * + cc and Ω * + cc are expected to be small as the contributions of the heavy quarks and light quark cancel out to some extent due to their opposite signs. However, in LCQSR [98], the contribution from the light quark dominates over two charm quarks, with a large magnitude leading to larger numerical values. ...
Motivated by the precision measurements of heavy flavor baryon masses, we analyze the modification of quark charge by employing the screening effect inside the baryon. In addition, we calculate the isospin mass splitting up to charmed baryons employing isospin symmetry breaking. Consequently, we obtain the masses, magnetic moments, and transition moments of $J^P=\frac{1}{2}^+$ and $\frac{3}{2}^+$ baryons to predict radiative decay widths for $\frac{1}{2}^{\prime +} \to \frac{1}{2}^+$ and $\frac{3}{2}^+\to \frac{1}{2}^{(\prime)+}$ transitions. Finally, we include the effects of state mixing in flavor degenerate baryon magnetic and transition moments, as well as M1 transition decay widths.
... For the spin- 1 2 doubly charmed baryons, their magnetic moments have been systematically investigated in the heavy-baryon (HB) chiral perturbation theory (χPT) [16,17], the extended on-mass shell (EOMS) baryon chiral perturbation theory (BχPT) [18,19], and the light cone QCD sum rule (LCSR) [20] after the discovery of Ξ þþ cc . Up to now, the magnetic moments of spin- 3 2 doubly charmed baryons have also been examined in a variety of phenomenological models [21][22][23][24][25][26][27], the LCSR [28], the HB χPT [29], and lattice QCD simulations [30]. It should be stressed that the lattice QCD study [30] only calculated the magnetic moment of Ω Ãþ cc for an unphysical m π ≈ 156 MeV. ...
... MeV is the nucleon mass. For the convenience of comparison with the magnetic moments of the doubly charmed baryons μ T obtained in other approaches [21][22][23][24][25][26][27][28][29]48], we take the nuclear magneton μ N as the units of μ T in this work. ...
Inspired by the discovery of the spin-12 doubly charmed baryon Ξcc++ and the subsequent theoretical studies of its magnetic moments, we study the magnetic moments of its spin-32 heavy quark spin symmetry counterparts, up to the next-to-leading order in covariant baryon chiral perturbation theory with the extended-on-mass-shell renormalization scheme. With the tree-level contributions fixed by the quark model while the two low energy constants C and H controlling the loop contributions determined in two ways: the quark model (case 1) and lattice QCD simulations together with the quark model (case 2), we study the quark mass dependence of the magnetic moments and compare them with the predictions of the heavy baryon chiral perturbation theory. It is shown that the difference is sizable in case 1, but not in case 2 due to the smaller low energy constants C and H, similar to the case of spin-12 doubly charmed baryons. Second, we predict the magnetic moments of the spin-32 doubly charmed baryons and compare them with those of other approaches. The predicted magnetic moments in case 2 for the spin-32 doubly charmed baryons are closer to those of other approaches. In addition, the large differences in case 1 and case 2 for the predicted magnetic moments may indicate the inconsistency between the quark model and the lattice QCD simulations, which should be checked by future experimental or more lattice QCD data.
... Specifying the magnetic moment provides important information on structure, size, and shape of hadrons as well as hadron properties based on quark-gluon degrees of freedom. Magnetic moments of the doubly-heavy baryons have been examined broadly in the literature, see [62,[90][91][92][93][94] for recent references. ...
Inspired by the discovery of the doubly-charmed and doubly-charged $\Xi_{cc}^{++}$ baryon, in this present work, we investigate spin-1/2 and spin-3/2 mass spectra and magnetic moments of $ccu$ baryon in quark-diquark model with a nonrelativistic potential. In the quark-diquark picture, the three-body problem of the $ccu$ baryon is reduced to the two-body bound state problem. We obtained ground and radially excited mass spectra and magnetic moments of the ground state. Ground state mass spectra agree well with the results in the literature, especially with lattice QCD computations. Predictions for the magnetic moment are compatible with the literature. According to our results, $cu$ diquark clustering in the $\Xi_{cc}^{++}$ baryon is more favorable than the $cc$ diquark clustering.
... The numerical results are shown in Table 5 for all doubly heavy baryon system. The obtained results are in accordance with the works in [53][54][55][56][57][58][59][60][61][62]. ...
We revisited the mass spectra of the Ξcc++ baryon with positive and negative parity states using Hypercentral Constituent Quark Model Scheme with Coloumb plus screened potential. The ground state of the baryon has been determined by the LHCb experiment, and the anticipated excited state masses of the baryon have been compared with several theoretical methodologies. The transition magnetic moments of all heavy baryons Ξcc++, Ξcc+, Ωcc+, Ξbb0, Ξbb−, Ωbb−, Ξbc+, Ξbc0, Ωbc0 are also calculated and their values are −1.013 μN, 1.048 μN, 0.961 μN, −1.69 μN, 0.73 μN, 0.48 μN, −1.39 μN, 0.94 μN and 0.710 μN, respectively.
... Beyond the quark models [38][39][40], many effective models like lattice QCD [41], Quark Spin Symmetry [42,43], QCD Sum Rules [22][23][24][25][26] and Light-Cone Sum Rules [19,20,[44][45][46][47][55][56][57][58] have been proposed to describe masses, residues, lifetimes, strong coupling constants, and other properties of doubly heavy baryons. Given that the expectations to discover more doubly heavy baryons are growing, we are witnessing the rise of further theoretical investigations in this respect. ...
... For the spin-1 2 doubly charmed baryons, their magnetic moments have been systematically investigated in the heavybaryon (HB) chiral perturbation theory (ChPT) [16,17], the extended on-mass shell (EOMS) BChPT [18,19] and the light-cone QCD sum rule (LCSR) [20] after the discovery of Ξ ++ cc . Up to now, the magnetic moments of spin- 3 2 doubly charmed baryons have also been examined in a variety of phenomenological models [21][22][23][24][25][26][27], the LCSR [28], and the HB ChPT [29]. ...
Inspired by the discovery of the spin-$\frac{1}{2}$ doubly charmed baryon $\Xi_{cc}^{++}$ and the subsequent theoretical studies of its magnetic moments, we study the magnetic moments of its spin-$\frac{3}{2}$ heavy quark spin symmetry counterparts, up to the next-to-leading order in covariant baryon chiral perturbation theory (BChPT) with the extended-on-mass-shell renormalization (EOMS) scheme. With the tree-level contributions and the two low energy constants (LECs) $C$ and $H$ controlling the loop contributions fixed by the quark model, we study the quark mass dependence of the magnetic moments and compare them with the predictions of the heavy baryon chiral perturbation theory (HB ChPT). It is shown that the difference is sizable such that they are relevant for future lattice QCD simulations. Second, we predict the magnetic moments of the spin-$\frac{3}{2}$ doubly charmed baryons and compare them with those of other approaches. We find that our predictions for $\Xi_{cc}^{*++}$ and $\Xi_{cc}^{*+}$ are smaller in absolute value than those of other approaches while that for $\Omega_{cc}^{*+}$ is larger, which should be checked by future experimental data or Lattice QCD simulations.
... Beyond the quark models [36][37][38], many effective models like lattice QCD [39], Quark Spin Symmetry [40,41], QCD Sum Rules [22][23][24][25][26] and Light-Cone Sum Rules [19,20,[42][43][44][45][46][47][48][49] have been proposed to describe masses, residues, lifetimes, strong coupling constants, and other properties of doubly heavy baryons. Given that the expectations to discover more doubly heavy baryons are growing, we are witnessing the rise of further theoretical investigations in this respect. ...
The strong coupling constants are basic quantities that carry information of the strong interactions among the baryon and meson multiplets as well as information on the natures and internal structures of the involved hadrons. These parameters enter to the transition matrix elements of various decays as main inputs and they play key roles in analyses of the experimental data including various hadrons. We determine the strong coupling constants among the doubly heavy spin-$ 3/2 $ baryons, $\Xi^*_{QQ'} $ and $\Omega^*_{QQ'}$, and light pseudoscalar mesons, $\pi$, $K$ and $\eta$, using the light-cone QCD. The values obtained for the strong coupling constants under study may be used in construction of the strong potentials among the doubly heavy spin-3/2 baryons and light pseudoscalar mesons.
Inspired by the discovery of the doubly charmed and doubly charged \(\Xi _{\text {cc}}^{++}\) baryon, in this present work, we investigate spin-1/2 and spin-3/2 mass spectra and magnetic moments of ccu baryon in quark–diquark model with a nonrelativistic potential. In the quark–diquark picture, the three-body problem of the ccu baryon is reduced to the two-body bound state problem. We obtained ground and radially excited mass spectra and magnetic moments of the ground state. Ground state mass spectra agree well with the results in the literature, especially with lattice QCD computations. Predictions for the magnetic moment are compatible with the literature. According to our results, cu diquark clustering in the \(\Xi _{\text {cc}}^{++}\) baryon is more favorable than the cc diquark clustering.
We calculate the magnetic moments of ground state JP=12+ and JP=32+ heavy flavor charm and bottom baryon states employing the concept of effective mass based on single gluon exchange interaction coupling to the spectator quarks in the nonrelativistic quark model. We exploit the current experimental information in the heavy flavor sector to estimate the interaction contributions to get the effective masses of the quarks inside the baryons. We study the spin 12′+→12+, 32+→12+, and 32+→12′+ transition moments for these baryons. We make robust predictions of the radiative M1 decay widths of singly, doubly, and triply heavy flavored baryons.
A comprehensive study of $b\to c$ weak decays of doubly heavy baryons is presented in this paper. The transition form factors as well as the pole residues of the initial and final states are respectively obtained by investigating the three-point and two-point correlation functions in QCD sum rules. Contributions from up to dimension-5 and dimension-6 operators are respectively considered for the two-point and three-point correlation functions. The obtained form factors are then applied to a phenomenological analysis of semi-leptonic decays.
We calculate the magnetic moments of ground state $J^P=\frac{1}{2}^+$ and $J^P=\frac{3}{2}^+$ heavy flavor charm and bottom baryon states employing the concept of effective mass based on single gluon exchange interaction coupling to the spectator quarks in the non-relativistic quark model. We exploit the current experimental information in the heavy flavor sector to estimate the interaction contributions to get the effective masses of the quarks inside the baryons. We study the spin $\frac{1}{2}^{'+} \rightarrow \frac{1}{2}^+$, $\frac{3}{2}^+ \rightarrow \frac{1}{2}^+$, and $\frac{3}{2}^+ \rightarrow \frac{1}{2}^{'+}$ transition moments for these baryons. We make robust predictions of the radiative M1 decay widths of singly, doubly, and triply heavy flavored baryons.
We calculate the strong coupling constants among the doubly heavy spin- $$ \frac{3}{2} $$ 3 2 baryons $$\Xi ^*_{QQ}$$ Ξ QQ ∗ and $$\Omega ^*_{QQ}$$ Ω QQ ∗ , with Q and $$ Q' $$ Q ′ being c or b quark, with light vector meson by means of the light-cone QCD sum rules. The matrix elements defining these vertices are described by four coupling constants $$ g_1$$ g 1 , $$ g_2$$ g 2 , $$ g_3$$ g 3 , and $$ g_4 $$ g 4 . The unwanted pollution coming from the doubly heavy spin- $$ \frac{1}{2} $$ 1 2 baryons are removed by a special ordering of Dirac matrices and selection of appropriate Lorentz structures. The strong coupling constants are basic parameters that carry information on the nature of the strong interaction among hadronic multiplets. Investigation of these parameters may help physicists in the construction of the strong potentials among the doubly heavy baryons and light vector mesons. The values obtained for the strong coupling constants may also help experimental groups in analyses of the data produced at various hadron colliders.
We calculate the strong coupling constants among the doubly heavy spin-$ \frac{3}{2} $ baryons $\Xi^*_{QQ}$ and $\Omega^*_{QQ}$, with $ Q $ and $ Q' $ being $ c$ or $ b $ quark, with light vector meson by means of the light-cone QCD sum rules. The matrix elements defining these vertices are described by four coupling constants $ g_1$, $ g_2$, $ g_3$, and $ g_4 $. The unwanted pollution coming from the doubly heavy spin-$ \frac{1}{2} $ baryons are removed by a special ordering of Dirac matrices and selection of appropriate Lorentz structures. The strong coupling constants are basic parameters that carry information on the nature of the strong interaction among hadronic multiplets. Investigation of these parameters may help physicists in the construction of the strong potentials among the doubly heavy baryons and light vector mesons. The values obtained for the strong coupling constants may also help experimental groups in analyses of the data produced at various hadron colliders.
We present a path-integral hadronization for doubly heavy baryons. The two heavy quarks in the baryon are approximated as a scalar or axial-vector diquark described by a heavy diquark effective theory. The gluon dynamics are represented by a NJL-Model interaction for the heavy diquarks and light quarks, which leads to an effective action of the baryon fields after the quark and diquark fields are integrated out. This effective action for doubly heavy baryon includes the electromagnetic and electroweak interactions, as well as the interaction with light mesons. We also verify the Ward-Takahashi identity at the baryon level, obtain the Isgur-Wise function for weak transitions, and calculate the strong coupling constant of the doubly heavy baryon and pion. Numerical studies are also performed.
We analyze the weak decay of doubly-heavy baryon decays into anti-triplets \(\Lambda _Q\) with light-cone sum rules. To calculate the decay form factors, both bottom and charmed anti-triplets \(\Lambda _b\) and \(\Lambda _c\) are described by the same set of leading twist light-cone distribution amplitudes. With the obtained form factors, we perform a phenomenology study on the corresponding semi-leptonic decays. The decay widths are calculated and the branching ratios given in this work are expected to be tested by future experimental data, which will help us to understand the underlying dynamics in doubly-heavy baryon decays.
We study the electromagnetic form factors of the doubly charmed baryons, using covariant chiral perturbation theory within the extended on-mass-shell scheme. Vector-meson contributions are also taken into account. We present results for the baryon magnetic moments, charge, and magnetic radii. While some of the chiral Lagrangian parameters could be set to values determined in previous works, the available lattice results for Ξcc+ and Ωcc+ only allow for robust constraints on the low-energy constant combination, c89(=−13c8+4c9). The couplings of the doubly charmed baryons to the vector mesons have been estimated assuming the Okubo-Zweig-Iizuka rule. We also give the expressions for the form factors of the double-beauty baryons considering the masses predicted in the framework of quark models. A comparison of our results with those obtained in heavy baryon chiral perturbation theory at the same chiral order is made.
Inspired by the recent discovery of the Ξcc++ by the LHCb Collaboration, we study the magnetic moments of the spin-1/2 doubly charmed baryons up to the next-to-leading order in covariant baryon chiral perturbation theory with the extended-on-mass-shell renormalization scheme. There are three low energy constants at this order: a1, a2, and ga. The latest lattice QCD simulations allow us to fix a combination of a1 and a2, while the axial-vector coupling ga can be determined in three different ways: by fitting to the lattice QCD data, by the quark model, or by the heavy antiquark diquark symmetry. The magnetic moments of the spin-1/2 doubly charmed baryons, Ξccd and Ξccs, can then be predicted. We compare our results with those obtained in the heavy baryon chiral perturbation theory and other approaches, and point out some inconsistencies between the lattice QCD simulations and the quark model.
The existence of doubly heavy flavor baryons has not been well established experimentally so far. In this Letter we systematically investigate the weak decays of the doubly charmed baryons, and , which should be helpful for experimental searches for these particles. The long-distance contributions are first studied in the doubly heavy baryon decays, and found to be significantly enhanced. Comparing all the processes, and are the most favorable decay modes for experiments to search for doubly heavy baryons.
We extend the chromomagnetic model by further considering the effect of color interaction. The effective mass parameters between quark pairs ($m_{qq}$ or $m_{q\bar{q}}$) are introduced to account both the effective quark masses and the color interaction between the two quarks. Using the experimental masses of hadrons, the quark pair parameters are determined between the light quark pairs and the light-heavy quark pairs. Then the parameters of heavy quark pairs ($cc$, $cb$, $bb$) are estimated based on simple quark model assumption. We calculate all masses of doubly and triply heavy-quark baryons. The newly discovered doubly charmed baryon $\Xi_{cc}$ fits into the model with an error of 12 MeV.
In most non-perturbative methods in hadron physics the calculations are started with a correlation function in terms of some interpolating and transition currents in $ x $-space. For simplicity, the calculations are then transformed to the momentum space by a Fourier transformation.To suppress the contributions of the higher states and continuum; and enhance the ground state contribution, Borel transformation as well as continuum subtraction are applied by the help of quark-hadron duality assumption. In the present study we work out the mathematics required for these processes in the case of light and multi-heavy hadrons. We address a well-known problem in subtraction of the effects of the higher states and continuum and discuss how we find finite results without any divergence by using an appropriate representation of the modified Bessel functions, appearing in the heavy quark propagator, and successive applications of the Borel transformations, which lead to more suppression of the higher states and continuum contributions. The results obtained can be used in determination of the spectroscopic and decay properties of the multi-heavy standard and non-conventional (exotic) systems in many non-perturbative methods, specially the QCD sum rules.
In this work, we investigate the chiral corrections to the magnetic moments of the spin-\(3\over 2\) doubly charmed baryons systematically up to next-to-next-to-leading order with the heavy baryon chiral perturbation theory. The numerical results are given up to next-to-leading order: \(\mu _{\varXi ^{*++}_{cc}}=2.61\mu _{N}\), \(\mu _{\varXi ^{*+}_{cc}}=-0.18\mu _{N}\), \(\mu _{\varOmega ^{*+}_{cc}}=0.17\mu _{N}\). As a by-product, we have also calculated the magnetic moments of the spin-\(3\over 2\) doubly bottom baryons and charmed bottom baryons: \(\mu _{\varXi ^{*0}_{bb}}=2.83\mu _{N}\), \(\mu _{\varXi ^{*-}_{bb}}=-1.33\mu _{N}\), \(\mu _{\varOmega ^{*-}_{bb}}=-1.54\mu _{N}\), \(\mu _{\varXi ^{*+}_{bc}}=3.22\mu _{N}\), \(\mu _{\varXi ^{*0}_{bc}}=-0.84\mu _{N}\), \(\mu _{\varOmega ^{*0}_{bc}}=-1.09\mu _{N}\).
We use the method of light-cone sum rules to study the electromagnetic transition of the $\Xi^{*++}_{cc}$ into $\Xi^{++}_{cc}\gamma$, whose decay width is estimated to be $13.7~{^{+17.7}_{-~7.9}}$ keV. This value is large enough for the $\Xi^{*++}_{cc}$ to be observed in the $\Xi^{++}_{cc}\gamma$ channel, and we propose to continually search for it in future LHCb and BelleII experiments.
The newly-discovered $\Xi_{cc}^{++}$ decays into the $ \Lambda_{c}^+ K^-\pi^+\pi^+$, but the experimental data has indicated that this decay is not saturated by any two-body intermediate state. In this work, we analyze the multi-body weak decays of doubly heavy baryons $\Xi_{cc}$, $\Omega_{cc}$, $\Xi_{bc}$, $\Omega_{bc}$, $\Xi_{bb}$ and $\Omega_{bb}$, in particular the three-body nonleptonic decays and four-body semileptonic decays. We classify various decay modes according to the quark-level transitions and present an estimate of the typical branching fractions for a few golden decay channels. Decay amplitudes are then parametrized in terms of a few SU(3) irreducible amplitudes. With these amplitudes, we find a number of relations for decay widths, which can be examined in future.
Very recently, the LHCb collaboration has observed in the final state \(\Lambda _c^+ K^-\pi ^+\pi ^+\) a resonant structure that is identified as the doubly charmed baryon \(\Xi _{cc}^{++}\). Inspired by this observation, we investigate the weak decays of doubly heavy baryons \(\Xi _{cc}^{++}\), \(\Xi _{cc}^{+}\), \(\Omega _{cc}^{+}\), \(\Xi _{bc}^{(\prime )+}\), \(\Xi _{bc}^{(\prime )0}\), \(\Omega _{bc}^{(\prime )0}\), \(\Xi _{bb}^{0}\), \(\Xi _{bb}^{-}\) and \(\Omega _{bb}^{-}\) and focus on the decays into spin 1 / 2 baryons in this paper. At the quark level these decay processes are induced by the \(c\rightarrow d/s\) or \(b\rightarrow u/c\) transitions, and the two spectator quarks can be viewed as a scalar or axial vector diquark. We first derive the hadronic form factors for these transitions in the light-front approach and then apply them to predict the partial widths for the semileptonic and nonleptonic decays of doubly heavy baryons. We find that the number of decay channels is sizable and can be examined in future measurements at experimental facilities like LHC, Belle II and CEPC.
A highly significant structure is observed in the Λc+K−π+π+ mass spectrum, where the Λc+ baryon is reconstructed in the decay mode pK−π+. The structure is consistent with originating from a weakly decaying particle, identified as the doubly charmed baryon Ξcc++. The difference between the masses of the Ξcc++ and Λc+ states is measured to be 1334.94±0.72(stat.)±0.27(syst.) MeV/c2, and the Ξcc++ mass is then determined to be 3621.40±0.72(stat.)±0.27(syst.)±0.14(Λc+) MeV/c2, where the last uncertainty is due to the limited knowledge of the Λc+ mass. The state is observed in a sample of proton-proton collision data collected by the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.7 fb−1, and confirmed in an additional sample of data collected at 8 TeV.
We have systematically investigated the spin-$\frac{3}{2}$ to spin-$\frac{1}{2}$ doubly charmed baryon transition magnetic moments to the next-to-next-to-leading order in the heavy baryon chiral perturbation theory (HBChPT). Numerical results of transition magnetic moments and decay widths are presented to the next-to-leading order: $\mu_{\Xi_{cc}^{*++}\rightarrow\Xi_{cc}^{++}}=-2.35\mu_{N}$, $\mu_{\Xi_{cc}^{*+}\rightarrow\Xi_{cc}^{+}}=1.55\mu_{N}$, $\mu_{\Omega_{cc}^{*+}\rightarrow\Omega_{cc}^{+}}=1.54\mu_{N}$, $\Gamma_{\Xi_{cc}^{*++}\rightarrow\Xi_{cc}^{++}}=22.0$ keV, $\Gamma_{\Xi_{cc}^{*+}\rightarrow\Xi_{cc}^{+}}=9.57$ keV, $\Gamma_{\Omega_{cc}^{*+}\rightarrow\Omega_{cc}^{+}}=9.45$ keV.
Motivated by the recent LHCb observation of doubly-charmed baryon $\Xi_{cc}^{++}$ in the $\Lambda_c^+ K^-\pi^+\pi^+$ final state, we analyze the weak decays of doubly heavy baryons $\Xi_{cc}$, $\Omega_{cc}$, $\Xi_{bc}$, $\Omega_{bc}$, $\Xi_{bb}$ and $\Omega_{bb}$ under the flavor SU(3) symmetry. Decay amplitudes for various semileptonic and nonleptonic decays are parametrized in terms of a few SU(3) irreducible amplitudes. We find a number of relations or sum rules between decay widths and CP asymmetries, which can be examined in future measurements at experimental facilities like LHC, Belle II and CEPC. Moreover once a few decay branching fractions are measured in future, some of these relations may provide hints for exploration of new decay modes.
The chiral corrections to the magnetic moments of the spin-$\frac{1}{2}$ doubly charmed baryons are systematically investigated up to next-to-next-to-leading order with heavy baryon chiral perturbation theory (HBChPT). The numerical results are calculated up to next-to-leading order: $\mu_{\Xi^{++}_{cc}}=-0.25\mu_{N}$, $\mu_{\Xi^{+}_{cc}}=0.85\mu_{N}$, $\mu_{\Omega^{+}_{cc}}=0.78\mu_{N}$. We also calculate the magnetic moments of the other doubly heavy baryons, including the doubly bottomed baryons (bbq) and the doubly heavy baryons containing a light quark, a charm quark and a bottom quark ($\{bc\}q$ and $[bc]q$): $\mu_{\Xi^{0}_{bb}}=-0.84\mu_{N}$, $\mu_{\Xi^{-}_{bb}}=0.26\mu_{N}$, $\mu_{\Omega^{-}_{bb}}=0.19\mu_{N}$, $\mu_{\Xi^{+}_{\{bc\}q}}=-0.54\mu_{N}$, $\mu_{\Xi^{0}_{\{bc\}q}}=0.56\mu_{N}$, $\mu_{\Omega^{0}_{\{bc\}q}}=0.49\mu_{N}$, $\mu_{\Xi^{+}_{[bc]q}}=0.69\mu_{N}$, $\mu_{\Xi^{0}_{[bc]q}}=-0.59\mu_{N}$, $\mu_{\Omega^{0}_{[bc]q}}=0.24\mu_{N}$.
We present a systematic investigation of the possible molecular states composed of a pair of doubly charmed baryons ($\Xi_{cc}\Xi_{cc}$) or one doubly charmed baryon and one doubly charmed antibaryon $(\Xi_{cc}\bar{\Xi}_{cc})$ within the framework of the one-boson-exchange-potential model. For the spin-triplet systems, we take into account the mixing between the ${}^3S_1$ and ${}^3D_1$ channels. For the baryon-baryon system $\Xi_{cc}\Xi_{cc}$ with $(R,I) = (\bar{3}, 1/2)$ and $(\bar{3}, 0)$, there exist loosely bound molecular states. For the baryon-antibaryon system $\Xi_{cc}\bar{\Xi}_{cc}$ with $(R,I) = (8, 1)$, $(8, 1/2)$ and $(8,0)$, there also exist deuteron-like molecules. The $B_{cc}\bar{B}_{cc}$ molecular states may be produced at LHC. The proximity of their masses to the threshold of two doubly charmed baryons provides a clean clue to identify them.
In this paper, the mass spectra are obtained for doubly heavy $\Xi$ baryons, namely, $\Xi_{cc}^{+}$, $\Xi_{cc}^{++}$, $\Xi_{bb}^{-}$, $\Xi_{bb}^{0}$, $\Xi_{bc}^{0}$ and $\Xi_{bc}^{+}$. These baryons are consist of two heavy quarks($cc$, $bb$ and $bc$) with a light($d$ or $u$) quark. The ground, radial and orbital states are calculated in framework of Hypercentral constituent quark model with coul- omb plus linear potential. Our outcomes are also compared with other predictions, thus, the average possible range of excited states masses of these $\Xi$ baryons can be determined. The study of the Regge trajectories are performed in (n, $M^{2}$) and (J, $M^{2}$) planes and their slopes and intercepts are also determined. Lastly, the ground state magnetic moments of these doubly heavy baryons are also calculated.
Doubly-heavy baryons, with two heavy and one light quarks, are expected to exist in QCD and their masses have been predicted in the quark model. However their existence is not well established so far in experiment. In this work, we explore the possibility of searching for and in the W-exchange processes, and . On the basis of perturbative calculations, we estimate the branching ratio of the first decay as , where ( ) are the ratios of the decay constants (lifetimes) of and . The branching ratio of is related to that of , and thereby a conjectured topology analysis leads to the range for the branching ratio as: . The decay would be reconstructed in the final state which is easy to access even at a hadron collider. Based on the two facts that abundant heavy quarks can be produced at a hadron collider like LHC, and the branching ratios of and are sizable, we urge our experimental colleagues to perform a search at LHCb. This will presumably lead to the discovery of the and , and precision measurements of the branching ratios in the future are helpful to investigate their decay mechanism.
We discuss the mass spectrum of $\Omega$ baryon with two heavy quarks and one light quark (\textit{ccs, bbs and bcs}). The main goal of the paper is to calculate the ground state masses and after that, the positive and negative parity excited states masses are also obtained within a Hypercentral Constituent quark model, using coulomb plus linear potential framework. We also added first order correction to the potential. The mass spectra upto 5S for radial excited states and 1P-5P, 1D-4D and 1F-2F states for orbital excited states are computed for $\Omega_{cc}$, $\Omega_{bb}$ and $\Omega_{bc}$ baryons. Our obtained results are compared with other theoretical predictions which could be a useful complementary tool for the interpretation of experimentaly unknown heavy baryon spectra. The Regge trajectory is constructed in both ($n_r$, $M^{2}$) and ($J$, $M^{2}$) planes for $\Omega_{cc}$,$\Omega_{bb}$ and $\Omega_{bc}$ baryons and their slopes and intercepts are also determined. Magnetic moments of doubly heavy $\Omega'$s are also calculated.
We study the P-wave charmed baryons using the method of QCD sum rule in the
framework of heavy quark effective theory (HQET). We consider systematically
all possible baryon currents with a derivative for internal rho- and
lambda-mode excitations. We have found good working window for the currents
corresponding to the rho-mode excitations for Lambda_c(2595), Lambda_c(2625),
Xi_c(2790) and Xi_c(2815) which complete two SU(3) 3F_bar multiplets of
J(P)=1/2(-) and 3/2(-), while the currents corresponding to the lambda-mode
excitations seem also consistent with the data. Our results also suggest that
there are two Sigma_c(2800) states of J(P)=1/2(-) and 3/2(-) whose mass
splitting is 14 \pm 7 MeV, and two Xi_c(2980) states whose mass splitting is 12
\pm 7 MeV. They have two Omega_c partners of J(P) = 1/2(-) and 3/2(-), whose
masses are around 3.25 \pm 0.20 GeV with mass splitting 10 \pm 6 MeV. All of
them together complete two SU(3) 6F multiplets of J(P)=1/2(-) and 3/2(-). They
may also have J(P)=5/2(-) partners. Xi_c(3080) may be one of them, and the
other two are Sigma_c(5/2(-)) and Omega_c(5/2(-)), whose masses are 85 \pm 23
MeV and 50 \pm 27 MeV larger.
As a continuation of our recent work on the electromagnetic properties of the doubly charmed Ξcc
baryon, we compute the charge radii and the magnetic moments of the singly charmed Σc
, Ωc
and the doubly charmed Ωcc
baryons in 2+1 flavor Lattice QCD. In general, the charmed baryons are found to be compact as compared to the proton. The charm quark acts to decrease the size of the baryons to smaller values. We discuss the mechanism behind the dependence of the charge radii on the light valence- and sea-quark masses. The magnetic moments are found to be almost stable with respect to changing quark mass. We investigate the individual quark sector contributions to the charge radii and the magnetic moments. The magnetic moments of the singly charmed baryons are found to be dominantly determined by the light quark and the role of the charm quark is significantly enhanced for the doubly charmed baryons.
We calculate the magnetic moments of low lying heavy flavor bottom baryons
using e?ective quark mass and shielded quark charge scheme. We obtain the
magnetic moments of both $J^P = 1/2^+$ and $J^P = 3/2^+$ baryon states. We
compare our predictions with other theoretical approaches.
We search for the production of doubly charmed baryons in e+e- annihilations at or near a center-of-mass energy of 10.58 GeV, in a data sample with an integrated luminosity of 232 fb-1 recorded with the BABAR detector at the PEP-II storage ring at the Stanford Linear Accelerator Center. We search for Ξcc+ baryons in the final states Λc+K-π+ and Ξc0π+, and Ξcc++ baryons in the final states Λc+K-π+π+ and Ξc0π+π+. We find no evidence for the production of doubly charmed baryons.
Basic physical characteristics of doubly heavy baryons are examined,
including spectroscopy (which is treated in the potential approach and
within the QCD sum rules framework), production mechanisms for various
interactions (the fragmentation model with preasymptotic twist
corrections of higher order in the baryon transverse momentum),
inclusive decays and lifetimes (operator expansion in the inverse powers
of the heavy quark masses), and exclusive decays (in the QCD sum rules
framework). The effective theory of heavy quarks is extended to systems
with two heavy quarks and one light quark. The masses, decay widths and
yields of doubly heavy baryons are calculated for the experimental
facilities now being operated or planned. Prospects for the detection
and observation of such baryons are discussed. The most interesting
physical effects involving hadrons are analyzed and their impact on the
theory of heavy quark dynamics is considered.
The masses and residues of the spin--3/2 doubly heavy baryons are calculated
within the QCD sum rules method. A comparison of our predictions with those
existing in the literature is also made.
We calculate mass spectra of charmed baryons within a relativistically covariant quark model based on the Bethe-Salpeter equation
in instantaneous approximation. Interactions are given by a linearly rising three-body confinement potential and a flavor-dependent
two-body force derived from QCD instanton effects. This model has already been successfully applied to the calculation of
light flavor baryon spectra and is now extended to heavy baryons. Within the same framework we compare the results to those
obtained with the more conventional one-gluon exchange potential.
The magnetic dipole moments of the spin-12 doubly heavy baryons are extracted in the framework of the light-cone QCD sum rule using the photon distribution amplitudes. The electromagnetic properties of the doubly heavy baryons encodes important information of their internal structure and geometric shape. The results for the magnetic dipole moments of doubly heavy baryons acquired in this work are compared with the predictions of the other theoretical approaches. The agreement of the estimations with some (but not all) theoretical estimations is good. © 2019 Journal of Micromechanics and Microengineering. All rights reserved.
In the framework of an extended bag model the magnetic moments, M1 transition moments, and decay widths of all ground-state heavy hadrons are calculated. For the heavy baryons containing three quarks of different flavors the effect of hyperfine mixing of the states is taken into account. The additional care is taken to get more accurate theoretical estimates for the mass splittings of heavy hadrons. The use of such improved values enables one to provide more accurate predictions for the decay widths. These values of the hyperfine splittings between baryons may be also useful for the further experimental searches of new heavy hadrons. For instance, we predict $M(\Xi_{cc}^{*})=3695\pm5$ MeV. The agreement of our results for the M1 decay rates with available experimental data is good. We also present a wide comparison of the predictions obtained in our work with the results obtained using various other approaches.
We study the mass spectra and radiative decays of doubly heavy baryons within the diquark picture in a relativized quark model. The diquark masses are firstly solved by the relativized quark potential, and then the diquarks are treated as the usual antiquarks. The masses and wave functions of doubly heavy baryons are obtained by solving the Schr\"odinger-type equation between the diquark and quark. The theoretical mass of the $J^P=1/2^+$ $\Xi_{cc}$ ground state is 3613 MeV, which is in good agreement with the new observation of the LHCb collaboration. The predicted mass gap between two $S$ wave states, $\Xi_{cc}^*$ ($J^P=3/2^+$) and $\Xi_{cc}$ ($J^P=1/2^+$), is 131 MeV. Given the quark-photon couplings, the radiative transitions of doubly heavy baryons are also estimated by using the realistic wave functions. The partial decay widths of $\Xi_{cc}^{*++} \to \Xi_{cc}^{++}\gamma$ and $\Xi_{cc}^{*+} \to \Xi_{cc}^+\gamma$ are predicted to be about 48 and 26 keV, respectively, which is quite significant. These predictions of doubly heavy baryons can provide helpful information for future experimental searches.
We have systematically studied the strong and radiative decays of the low-lying $1P$-wave doubly charmed baryons. Some interesting observations are: (i) The states $\Xi_{cc}^*$ and $\Omega_{cc}^*$ with $J^P=3/2^+$ have a fairly large decay rate into the $\Xi_{cc}\gamma$ and $\Omega_{cc}\gamma$ channels with a width $\sim 15$ and $\sim7$ keV, respectively. (ii) The lowest lying excited doubly charmed baryons are dominated by the $1P$ $\rho$ mode excitations, which should be quite narrow states. They decay into the ground state with $J^P=1/2^+$ through the radiative transitions with a significant ratio. (iii) The total decay widths of the first orbital excitations of $\lambda$ mode ($1P_{\lambda}$ states with $J^P=1/2^-$, $3/2^-$, $5/2^-$) are about $\Gamma\sim100$ MeV, and the ratio between the radiative and hadronic decay widths is about $\mathcal{O}(10^{-3})$.
The possible QCD exotic states in the doubly charmed baryon sector are studied in this work. Within the chiral effective theory, it is predicted that several excited baryons result from the $S$-wave scattering of ground-state doubly charmed baryons ($\Xi_{cc}^{++}, \Xi_{cc}^{+}, \Omega_{cc}^{+}$) and light pseudoscalar mesons ($\pi, K, \eta$). The excited doubly charmed baryons can be classified by the strangeness ($S$) and isospin ($I$) quantum numbers. Among of the excited states, two of them are clearly exotic, in the sense that they can not be explained by the conventional baryons with three quarks, since their quantum numbers are $(S,I)=(1,0)$ and $(-1,1)$. Similar to the charmed scalar meson $D_{s0}^{*}(2317)$ in the $DK$ scattering and the hyperon $\Lambda(1405)$ in the $\bar{K}N$ scattering, one bound state below the $\Xi_{cc} \bar{K}$ threshold is predicted in the $(S,I)=(-1,0)$ channel. In addition, two resonant structures are found in the $\Xi_{cc}\pi, \Xi_{cc}\eta$ and $\Omega_{cc} K$ coupled-channel scattering with $(S,I)=(0,1/2)$. The corresponding pole positions and coupling strengths of the excited doubly charmed baryons are given. The scattering lengths of the ground-state doubly charmed baryons and light pseudoscalar mesons are also predicted. The current study may provide useful guides for future experimental measurements and lattice simulations.
We systematically study the $S$-wave doubly charmed baryons using the method of QCD sum rules. Our results suggest that the $\Xi_{cc}^{++}$ recently observed by LHCb can be well identified as the $S$-wave $\Xi_{cc}$ state of $J^P = 1/2^+$, while it may also be identified as the $S$-wave $\Xi_{cc}$ state of $J^P = 3/2^+$. We study their relevant $\Omega_{cc}$ states, whose masses are predicted to be around 3.7 GeV. We also systematically study the $P$-wave doubly charmed baryons, whose masses are predicted to be around 4.1 GeV. Especially, there can be several excited doubly charmed baryons in this energy region, and we suggest to search for them in order to study the fine structure of the strong interaction.
finite size of a doubly heavy diquark yields a positive correction to baryon masses calculated in the local-diquark approximation. Upon evaluating this correction for the ground states of doubly charmed baryons, it became possible to obtain new predictions of importance for current searches of these baryons in LHCb experiments: \(m[\Xi _{cc}^{1/{2^{ + + }}}] \approx m[\Xi _{cc}^{1/{2^{ + + }}}]\) = 3615 ± 55 MeV and \(m[\Xi _{cc}^{3/{2^{ + + }}}] \approx m[\Xi _{cc}^{3/{2^{ + + }}}]\) 3747 ± 55 MeV
The full version of QCD light-cone sum rule method is applied to tetraquarks containing a single heavy $b$ or $c$ quark. To this end, investigations of the strong vertices $X_{b}X_{b}\rho$ and $X_{c}X_{c}\rho$ are performed, where $X_b=[su][\bar b\bar d]$ and $X_c=[su][\bar c\bar d]$ are the exotic states built of four quarks of different flavors. The strong coupling constants $G_{X_{b}X_{b}\rho}$ and $G_{X_{c}X_{c}\rho}$ corresponding to these vertices are found using the $\rho$-meson leading and higher-twist distribution amplitudes. In the calculations $X_{b(c)}$ are treated as scalar bound states of a diquark and antidiquark.
The chiral dynamics of the doubly heavy baryons is solely governed by the
light quark. In this work, We have derived the chiral corrections to the mass
of the doubly heavy baryons up to N$^3$LO. The mass splitting of $\Xi_{cc}$ and
$\Omega_{cc}$ at the N$^2$LO depends on one unknown low energy constant $c_7$.
With the experimental mass of $\Xi_{cc}(3520)$ as the input, we estimate the
mass of $\Omega_{cc}$ to be around 3.678 GeV. Moreover, we have also performed
a systematical analysis of the chiral corrections to the axial currents and
axial charges of the doubly heavy baryons. The chiral structure and analytical
expressions will be very useful to the chiral extrapolations of the future
lattice QCD simulations of the doubly heavy baryons.
The large number of $B_c$ mesons observed by LHCb suggests a sizable cross
section for producing doubly-heavy baryons in the same experiment. Motivated by
this, we estimate masses of the doubly-heavy $J=1/2$ baryons $\Xi_{cc}$,
$\Xi_{bb}$, and $\Xi_{bc}$, and their $J=3/2$ hyperfine partners, using a
method which accurately predicts the masses of ground-state baryons with a
single heavy quark. We obtain $M(\Xi_{cc}) = 3627 \pm 12$ MeV, $M(\Xi_{cc}^*)=
3690 \pm 12$ MeV, $M(\Xi_{bb}) = 10162 \pm 12$ MeV, $M(\Xi_{bb}^*)= 10184 \pm
12$ MeV, $M(\Xi_{bc}) = 6914 \pm 13$ MeV, $M(\Xi'_{bc}) = 6933 \pm 12$ MeV, and
$M(\Xi_{bc}^*) = 6969 \pm 14$ MeV. As a byproduct, we estimate the hyperfine
splitting between $B_c^*$ and $B_c$ mesons to be $68 \pm 8$ MeV. We discuss
P-wave excitations, production mechanisms, decay modes, lifetimes, and
prospects for detection of the doubly heavy baryons.
We review the description of the lowest-energy nucleon excitation—the Δ(1232)Δ(1232)-resonance. Much of the recent experimental effort has been focused on the precision measurements of the nucleon-to-ΔΔ transition by means of electromagnetic probes. We confront the results of these measurements with the state-of-the-art calculations based on chiral effective-field theories (EFT), lattice Quantum Chromodynamics (QCD), large-NcNc relations, perturbative QCD, and QCD-inspired models. We also discuss the link of the nucleon-to-ΔΔ form factors to generalized parton distributions (GPDs). Some of the theoretical approaches are reviewed in detail, in particular, recent dynamical and unitary-isobar models of pion electroproduction, which are extensively used in the interpretation of experiments. A novel extension of chiral EFTs to the energy domain of the ΔΔ-resonance is reviewed. The two-photon exchange effects in the electroexcitation of the ΔΔ-resonance are addressed.
The modern status of basic low energy QCD parameters is reviewed. It is
demonstrated that the recent data allow one to determine the light quark
mass ratios with an accuracy of 10 15%. The general analysis of vacuum
condensates in QCD is presented, including those induced by external
fields. The QCD coupling constant α(mτ2) is found
from the τ-lepton hadronic decay rate. The contour improved
perturbation theory includes the terms up to αs4. The influence of
instantons on α(mτ2) determination is estimated.
V-A spectral functions of the τ-decay are used for
construction of the V-A polarization operator Π(s)
in the complex s-plane. The operator product expansion (OPE) is used up
to dimension D=10 and the sum rules along the rays in the complex
s-plane are constructed. This makes it possible to separate the
contributions of operators of different dimensions. The best values of
the quark condensate and α< are found.
The value of the quark condensate is confirmed by considering the sum
rules for baryon masses. The value of the gluon condensate is found in
four ways: by considering the V+A polarization operator based on the
τ-decay data and by studying the sum rules for polarization operator
momenta in charmonia in the vector, pseudoscalar and axial channels. All
of these determinations are in agreement and result in
<(α/π)G>=0.005±0.004GeV.
Valence quark distributions in the proton are calculated in QCD using
the OPE in the proton current virtuality. The quark distributions agree
with those found from the deep inelastic scattering data. The same value
of the gluon condensate is favoured.
The spectra of baryons which include two heavy quarks can be treated as a two-body system, where the two heavy quarks constitute a bosonic diquark. We derive the effective potential between the light quark and the heavy diquark in terms of the Bethe-Salpeter equation. To obtain the spectra, several serious problems need to be solved: (1) the operator ordering, (2) the errors caused by the nonrelativistic expansion, (3) spin-spin coupling, and (4) the mixing between the scalar-diquark-baryon and vector-diquark-baryon. In this work we take reasonable approaches to deal with them.
We compute the electromagnetic properties of \Xi_cc baryons in 2+1 flavor
Lattice QCD. By measuring the electric charge and magnetic form factors of
\Xi_cc baryons, we extract the magnetic moments, charge and magnetic radii as
well as the \Xi_cc \Xi_cc \rho coupling constant, which provide important
information to understand the size, shape and couplings of the doubly charmed
baryons. We find that the two heavy charm quarks drive the charge radii and the
magnetic moment of \Xi_cc to smaller values as compared to those of, e.g., the
proton.
Spectra of masses are calculated for the families of doubly heavy baryons in the framework of the nonrelativistic quark model with the QCD potential of Buchmüller and Tye. We suppose the quark-diquark structure for the wave functions and take into account the spin-dependent splittings. The physical reasons causing the existence of quasistable excited states in the subsystem of heavy diquark are considered for the heavy quarks of identical flavors.
We compute the magnetic moments of charmed baryons using the gauge-theory quark model of De Rújula, Georgi, and Glashow. We find that these moments are quite different (sometimes differing in sign as well as magnitude) from those computed by Choudhury and Joshi, who used U(8) symmetry. The reason for the difference is that in our calculation the heavy mass of the charmed quark badly breaks U(8) symmetry. Our results reduce essentially to those of Choudhury and Joshi when all quark masses are set equal to one another.
The mass spectrum of charmed and bottom baryons is computed on anisotropic lattices using quenched lattice nonrelativistic QCD. The masses are extracted by using mass splittings which are more accurate than masses obtained directly by using the nonrelativistic mass-energy relation. Of particular interest are the mass splittings between spin-1/2 and spin-3/2 heavy baryons, and we find that these color hyperfine effects are not suppressed in the baryon sector although they are known to be suppressed in the meson sector. The results are compared with those obtained in a previous nonrelativistic QCD calculation and with those obtained from a Dirac-Wilson action of the D234 type.
We investigate the charmed baryon mass spectrum using the relativistic heavy
quark action on 2+1 flavor PACS-CS configurations previously generated on $32^3
\times 64$ lattice. The dynamical up-down and strange quark masses are tuned to
their physical values, reweighted from those employed in the configuration
generation. At the physical point, the inverse lattice spacing determined from
the $\Omega$ baryon mass gives $a^{-1}=2.194(10)$ GeV, and thus the spatial
extent becomes $L = 32 a = 2.88(1)$ fm. Our results for the charmed baryon
masses are consistent with experimental values, except for the mass of
$\Xi_{cc}$, which has been measured by only one experimental group so far and
has not been confirmed yet by others. In addition, we report values of other
doubly and triply charmed baryon masses, which have never been measured
experimentally.
We present here the ratios of the magnetic moments of the charmed and
b-flavored hadrons to the proton magnetic moment, calculated in the MIT
bag model, incorporating the corrections due to nonsphericity of the bag
containing heavy quarks.
We compute the masses of the ground state baryons and their spin excited
states discussing quark wave functions in baryons. Doubly charmed baryon
masses are given in the expected accuracy of +/-10 MeV.
Magnetic moments of J = 1/2 and J = 3/2 heavy baryons are calculated in the
bag model with center-of-mass motion corrections. For the spin 1/2 baryons
containing three quarks of different flavours the effect of hyperfine mixing is
examined in detail. The results of the work are compared with predictions
obtained in various other approaches and models.
We suggest a modification of the QCD sum rules for three-point correlation functions that relates hadron expectation values of an operator of interest to properties of the QCD vacuum in alternating external fields. A new sum rule is obtained for the nucleon magnetic moments. Relations are found between the couplings gNN
, g and the value of the pion wave function at the point with equal momentum carried by the quark and the antiquark. Our results seem to exclude the possibility of having a pronounced dip in the pion wave function in the middle point, as has been assumed on the evidence of a large value of the second moment.
Using several realistic interquark potentials, the ground-state energies of all the baryons containing one, two or three
heavy quarks of type c or b are studied within a non-relativistic quark model. The three-body problem is rigorously solved using the Faddeev formalism.
Various static properties, such as mass radii, charge radii, magnetic moments, and wave functions at the origin are calculated
as well. The complete spectrum for all these baryons is computed using a harmonic-oscillator basis with states up to 8 quanta.
Emphasis is put on the levels lying below the thresholds corresponding to quark-pair creation.
The masses of charmed baryons with spin 1/2 (Λ
c
+,Σ
c
++) and their residues into quark currents are calculated on the basis of QCD sum rules method. The obtained values of masses are in good agreement with experiment. Arguments are given in favour of existence of resonance Σ
c
++
* with negative parity and mass close to 2, 6 GeV.